Modern guided missiles need high performance gas generators for providing gas to control nozzles of post-boost control systems. This provides gas energy to achieve forward, reverse, pitch, yaw and roll control of the missile equipment and re-entry body sections. Prior art techniques have not provided the high performance required for advanced weapon systems that must undergo severe operating environments and have high pressure long time period burn requirements. Moreover, a modern weapon system often has long storage life requirements wherein propellants that have excessively aged may be inexpensively replaced with fresh propellants. These and other requirements have been accomplished by the gas generator solid propellant grain assembly of the present invention.